package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {


    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    @Override
    public Result queryById(Long id) {



        //-----------------------------------/
        // 解决缓存穿透
       Shop shop = cacheClient
               .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
       // this::getById 等同于id2->getByID(id2)

         //互斥锁解决缓存击穿
//        Shop shop=queryWithMutex(id);
//         Shop shop = cacheClient
//                .queryWithMutex(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

         //逻辑过期解决缓存击穿
//        Shop shop=queryWithLogicalExpire(id);
//        Shop shop = cacheClient
//                 .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);

        if (shop == null) {
           return Result.fail("店铺不存在！");
        }
        // 7.返回
       return Result.ok(shop);
    }
//------------------------逻辑过期------------------------------
    public Shop queryWithLogicalExpire(Long id)
    {
        //        1.从redis查询商铺缓存
        String key= CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        2.未命中 返回不null
        if(StrUtil.isBlank(shopJson))
        {
            return null;
        }
        //4. 命中需要判断过期时间 把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        //本质返回的是JSONObject
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
         if(expireTime.isAfter(LocalDateTime.now()))
         {
              //5.1 未过期 直接返回店铺信息
             return shop;
         }
        //5.2 已过期，需要缓存重建
        //6.缓冲重建
        //6.1 获取互斥锁
        String lockKey= LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取锁成功
        if (isLock) {
            //6.3 成功 开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit( ()->{ //lamb表达式

                try{
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });
        }
        //6.4 返回过期的商铺信息
        return shop;
    }
    //-----------------------------------------//
    //互斥锁缓存击穿
    public Shop queryWithMutex(Long id)
    {
        //        1.从redis查询商铺缓存
        String key= CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        2.判断是否存在
        if(StrUtil.isNotBlank(shopJson))
        {
            //        3. 存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson!=null)
        {
            return null;
        }
        //4.开始实现缓存重建
//        4.1 获取互斥锁

        String lockKey= LOCK_SHOP_KEY+id;

        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
//            4.2 判断是否获取成功
            if (!isLock) {
                //            4.3 失败，则休眠重试
                Thread.sleep(50);
               return  queryWithMutex(id);
            }
//            4.4 成功 根据id查询数据库
            shop = getById(id);
            //模拟重建的延时 增加并发的冲突，解决线程安全问题  利用JMETER压测工具进行高并发环境模拟
            Thread.sleep(200);
//        5.不存在，返回不错误
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
//        6.存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //        7 释放互斥锁
            unlock(lockKey);
        }
//        8返回
        return shop;
    }
//    以下是缓存穿透的代码
//    public Shop queryWithPassThrough(Long id)
//    {
//        //        1.从redis查询商铺缓存
      //  String key= CACHE_SHOP_KEY+id;
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
////        2.判断是否存在
//        if(StrUtil.isNotBlank(shopJson))
//        {
//            //        3. 存在，直接返回
//            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
//            return shop;
//        }
//        if(shopJson!=null)
//        {
//            return null;
//        }
////        4.不存在，根据ID查询数据库
//        Shop shop=getById(id);
////        5.不存在，返回不错误
//        if(shop==null)
//        {
//            //将空值写入redis
//            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
//            return null;
//        }
////        6.存在，写入redis
//        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL,TimeUnit.MINUTES);
////        7.返回
//        return shop;
//    }
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }
    //封装了一个存储用户信息和逻辑过期时间的函数，可以说是key永久有效了
     public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
         //1.查询店铺信息
         Shop shop=getById(id);
         Thread.sleep(200);
         //2.封装逻辑过期时间
         RedisData redisData = new RedisData();
         redisData.setData(shop);
         redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
         //3.写入Redis
         stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
     }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
